The VCL provides another function used to calculate the
depreciation of an item. This time, the depreciation is considered on one
period of the life of the item. The function used, SLNDepreciation(), is:

The Cost argument is the original amount paid
for an item (refrigerator, mechanics toolbox, high-volume printer, etc).
The Life parameter represents the period during which the asset is
(or was) useful; it is usually measured in years. The Salvage
parameter, also called the scrap value, is the value that the item will
have (or is having) at the end of Life.